Association between vascular risk factors and white matter integrity among diverse predominantly older...

Cerebral small vessel disease is a major contributor to stroke and cognitive decline and is characterized by white matter hyperintensities (WMH) and microstructural alterations detectable via diffusion-weighted imaging parameters, including free water (FW) and fractional anisotropy (FA). Hispanic/Latino populations experience a high burden of vascular risk factors. However, the impact of these factors on white matter integrity across diverse heritage groups remains underexplored in this population. This study aimed to investigate the association between vascular risk factors and MRI measures of white matter changes in cognitively normal Hispanic/Latino adults. This study was conducted on 1619 cognitively normal participants from the SOL-INCA MRI cohort. MRI data were acquired using standardized 3-T protocols, and white matter integrity measures, including FW, FA, and WMH, were obtained for white matter and specific white matter tracts. Linear regression models were conducted to assess the associations of vascular risk factors (hypertension, diabetes, total cholesterol ≥ 200 mg/dL, and ever-smoking) and Hispanic/Latino heritage with white matter integrity measures, adjusting for age, sex, education, and field center. Fully adjusted regression models revealed significant differences between heritage groups in FW and WMH, with Cuban participants having higher levels of FW and WMH and Puerto Rican participants having higher levels of WMH as compared to Mexican participants (p < 0.05). Hypertension and diabetes were associated with higher FW and WMH (p < 0.001), and diabetes was associated with lower FA values (p < 0.001). No significant interactions were found between vascular risk factors and Hispanic/Latino heritage, except for smoking status. Smoking was associated with higher FW and lower FA among Cuban and Puerto Rican participants, and lower FA in Central/South Americans, compared to Mexicans (p < 0.05). Tract-level analyses reflected overall trends, with more impaired white matter MRI measures in Cuban and Puerto Rican participants. Our study indicates significant differences in white matter integrity among participants of different Hispanic/Latino heritage, even after accounting for vascular risk factors. These findings highlight the importance of considering within-group heterogeneity in studies of brain aging, warranting further investigation into possible factors that may contribute to these observed differences.